Postural instability and impaired dynamic balance control are often ineffectually treated symptoms of Parkinson's Disease (PD) leading to an increased risk of falls. Patients often resort to the use of attentional strategies to maintain stability during the performance of gait and postural tasks. These attention-directed strategies appear unsuccessful when patients are required to perform concurrent or dual tasks. Thus, the development of rehabilitation strategies aimed at improving not only postural stability but also dual task performance in this population is paramount. This pilot proposal is directly related to the mission of NCMRR to enhance the health, productivity, independence, and quality of life of persons with disabilities. Substantial evidence suggests that Tai Chi (TC) is instrumental in preventing falls among community-dwelling older adults. The PIs suggest that one means by which TC leads to a reduction in falls is through reducing dual task interference on postural stability. A critical first step in evaluating this potential mechanism is critically challenging this hypothesis in populations where postural stability is markedly challenged under dual task conditions. The general hypothesis is that TC improves both static and dynamic postural control during dual task conditions in patients with mild to moderate idiopathic PD. This hypothesis will be tested with 3 specific aims to (1) determine if TC training improves postural control during quiet stance under dual task conditions, (2) determine if Tai Chi training improves dynamic postural control during forward directed locomotion under dual task conditions, and (3) determine if Tai Chi training improves dynamic postural control during perturbed locomotion under dual task conditions. Twenty four patients will be randomized to receive either intense TC training (N=16; 75 minutes/ 3xweek for 16wks) or non exercise control (N=8) in a single blind manner. The primary outcome measures, postural sway, gait performance (gait velocity, stride length, gait variability), and dynamic stability (coupling of the center of pressure and center of mass), will be compared pre- and post-training/control using mixed model MANOVA and ANOVAs. This pilot investigation will demonstrate whether TC improves postural control during balance and gait tasks of increasing difficulty that are performed concomitantly with either a cognitive or upper extremity motor task. The long term goal is to identify postural mechanisms associated with a learning of TC and improve rehabilitation programs for adults with mobility impairments. [unreadable] [unreadable] One of most pressing contemporary research and public health priorities (specifically for the National Institute of Child Health and Human Development) focuses on the need to enhance the health, productivity, independence, and quality of life of persons with disabilities. The current proposal describes a 16-week randomized, single-blind control of Tai Chi Exercise that has the potential for significant utility in reducing Parkinsonian disability as well reducing the known dual task performance interference on locomotor and postural control in individuals with Parkinson's disease. [unreadable] [unreadable] [unreadable]